Linear transmission member driving unit for endoscope

BACKGROUND OF THE INVENTION

This application claims the priority of Japanese Patent Application No. 2000-266437 filed on Sep. 4, 2000 which is incorporated herein by reference.

1. Field of the Invention

The present invention relates to a linear transmission member driving unit for an endoscope, and more particularly to a structure of a driving unit for rotating, by means of a motor, a linear transmission member for changing an observation distance.

2. Description of the Prior Art

In recent years, for the endoscope, there has been proposed an endoscope, to which a mechanism for making an observation distance (or depth of field) variable has been applied (disclosed in, for example, Japanese Patent Laid-Open No. 2000-111806 specification or the like). More specifically, a movable lens for making the observation distance variable is installed in an objective optical system arranged at a tip end portion of the endoscope in such a manner that this movable lens can be driven by means of a linear transmission member consisting of a multiple coiled spring or the like. This linear transmission member is arranged together with a protective tube from the tip end portion to an operating unit of the endoscope, and is coupled to a motor provided within this operating unit. In this respect, the protective tube contains the linear transmission member, whereby it is possible to avoid any interference with other members within the endoscope.

According to such a structure, rotation of the motor is transmitted to a driving unit at the tip end portion by means of the linear transmission member to thereby move the movable lens back and forth through this driving unit, whereby it becomes possible to change the observation distance to be set by the objective optical system. This observation distance is operated by a switch provided in the operating unit or the like so that a focal length can be changed to a far direction or a near direction.

BRIEF SUMMARY OF THE INVENTION

Object of the Invention

In the linear transmission member driving unit for the endoscope, however, the linear transmission member consisting of a multiple coiled spring or the like is contained within the protective tube as described above, and an insertion portion (tip end portion, angle portion and soft portion) of the endoscope is requested to have as fine a diameter as possible, and the protective tube to be arranged within the insertion portion is also formed to be as fine as possible, and therefore, there is a problem that friction between the protective tube and the linear transmission member deteriorates the transmission efficiency of motor rotation.

Also, as the endoscope, various types such as gastroscopes and large intestine scopes have been manufactured, and since each of these endoscopes differs in diameter and length of their insertion portions, the respective protective tubes for them must be also adjusted in diameter and length for each type. On the other hand, on the operating unit side, in which the motor driving unit is arranged, it has been requested to standardize the structure of the driving unit including the protective tube irrespective of the type of the endoscope.

The present invention has been achieved in the light of the above-described problems, and is aimed to provide a linear transmission member driving unit for an endoscope capable of enhancing transmission efficiency of the motor driving force by reducing friction between the linear transmission member and the protective tube as far as possible and making the structure of the driving unit within the operating unit identical even when the endoscope is different in type.

SUMMARY OF THE INVENTION

In order to attain the above-described object, there is provided a linear transmission member driving unit for an endoscope according to the present invention, in which the linear transmission member and a protective tube therefor are arranged from a tip end portion to an operating unit, for rotating the linear transmission member by means of a motor to thereby drive an object at the tip end portion, wherein the protective tube is divided into a front-side tube and a rear-side tube having a larger inner diameter than the front-side tube, and the front-side tube and the rear-side tube are connected together within the operating unit.

Also, the linear transmission member can be also divided into a front-side transmission member and a rear-side transmission member having a larger outside diameter than the front-side transmission member.

Another invention is characterized in that a multiple coiled spring formed by winding strands of a predetermined number of threads brought into tight contact in a state, in which space for predetermined intervals is left, is used as the above-described rear-side transmission member.

According to the above-described structure, in the rear-side tube having a larger inner diameter arranged within the operating unit, friction with the linear transmission member is reduced so that the transmission efficiency of the motor can be enhanced. Also, this rear-side tube has an advantage that it can be made to have a constant thickness irrespective of the type of the endoscope.

According to another invention described above, the rear-side transmission member is to be formed by winding strands every four or five pieces while space for, for example, a single thread is left, and this spiral space for a single thread is capable of reducing the friction between the rear-side transmission member and the protective tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a view showing an overall structure of an endoscope according to an embodiment of the present invention. In this respect, an angle portion <b>10</b>B and a soft portion <b>10</b>C are drawn with their length reduced;

FIG. 1B is a view showing a structure of a linear transmission member driving unit according to the embodiment;

FIG. 2 is a view for a protective tube showing detail of the linear transmission member driving unit for the endoscope of FIG. 1A;

FIG. 3 is a view showing a linear transmission member for the linear transmission member driving unit of FIG. 1B;

FIG. 4 is a view for a motor driving unit within the operating unit, showing the detail of the driving unit according to the embodiment; and

FIG. 5 is a view showing a lens driving unit within a tip end portion of the endoscope according to the embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Each drawing shows a linear transmission member driving unit for an endoscope (electronic endoscope) according to the embodiment, and as shown in FIG. 1A, an endoscope <b>10</b> has a tip end portion <b>10</b>A, an angle portion <b>10</b>B, a soft portion <b>10</b>C and an operating unit <b>10</b>D, and is connected to a processor or the like through a cable <b>11</b>. At a connecting portion between the operating unit <b>10</b>D and the soft portion <b>10</b>C, there is provided cover rubber <b>12</b>, and in this operating unit <b>10</b>D, there are arranged an air supply/water supply switch <b>13</b>A, a suction switch <b>13</b>B, a photograph switch <b>14</b>, a switch <b>15</b> for making the observation distance variable, or the like.

FIGS. 4 and 5 show the detail of the interior, and FIG. 4 shows a structure of the motor driving unit within the operating unit <b>10</b>D. As shown, to a chassis <b>17</b>, a motor (tip-end side) <b>19</b> is mounted through a holding member (rear-side mounting portion) <b>18</b> of the driving unit, and to the front-side mounting portion of the holding member <b>18</b>, there is held and fixed a protective tube <b>21</b> containing a net through a fixture <b>20</b>.

To a rotating shaft of the motor <b>19</b>, there is mounted a shaft connecting member <b>24</b> constituting a movable shaft coupling mechanism by means of a shaft fixing portion <b>23</b>. More specifically, this shaft connecting member <b>24</b> has a main body as a cylindrical element. For example, at two places opposite to each other on a wall of this cylindrical element, there are formed sliding guide holes <b>24</b>A along the rotating shaft direction <b>100</b>, and on the tip end side, there is mounted a stopper ring <b>25</b>. Also, the end portion of a linear transmission member <b>27</b> consisting of a multiple coiled spring or the like inserted into the protective tube <b>21</b> is fixed to a sleeve <b>28</b>, which is mounted with a pin <b>29</b> in a direction perpendicular to the rotating shaft direction <b>100</b>.

Therefore, this shaft connecting member <b>24</b> transmits the rotation of the motor <b>19</b> to the linear transmission member <b>27</b>, and slides the pin <b>29</b> along the guide hole <b>24</b>A to thereby play a role of moving the rear end of the linear transmission member <b>27</b> in the rotating shaft direction <b>100</b>. As a result, the linear transmission member <b>27</b> advances or retracts in response to an angle bending operation not to expand or contract by itself any longer, making it possible to perform a stable driving operation. Also, at the shaft fixing portion <b>23</b>, there is provided a wall-shaped protruded portion <b>23</b>A along the axial direction, a locking pin portion <b>30</b> for locking this protruded portion <b>23</b>A is formed as a setscrew. These function as a rotary stopper mechanism, and after securing a predetermined range of rotation of the linear transmission member <b>27</b>, the rotation of the shaft connecting member <b>24</b> is stopped. This stoppage eliminates any kink of the linear transmission member <b>27</b> to thereby improve the response of the driving control.

FIG. 5 shows a structure of the lens driving unit within the tip end portion <b>10</b>A. In this tip end portion <b>10</b>A, there is provided an objective optical system consisting of a front-side lens <b>33</b>, two movable lenses <b>34</b>A and <b>34</b>B for changing the observation distance, and a rear-side lens <b>35</b>, and to this objective optical system, there is optically connected a CCD<b>37</b> through a prism <b>36</b>. On a holding member for the movable lenses <b>34</b>A and <b>34</b>B, there are integrally provided cylindrical portions <b>40</b>A and <b>40</b>B having through-holes, through which a rotary driving element <b>39</b> coupled to the linear transmission member <b>27</b> is inserted.

And, on the inner walls of the cylindrical portions <b>40</b>A and <b>40</b>B, there are provided pins <b>41</b>, and on the outer periphery of the other rotary driving element <b>39</b>, there are formed cam grooves <b>42</b>A and <b>42</b>B for engaging with the pins <b>41</b>, and this rotary driving element <b>39</b> and the cylindrical portions <b>40</b>A and <b>40</b>B function as the guide member. Therefore, when the rotation of the linear transmission member <b>27</b> is transmitted to the rotary driving element <b>39</b>, this rotation is converted into a straight-line motion by means of the engagement between the cam grooves <b>42</b>A and <b>42</b>B and the pins <b>41</b> of the cylindrical portions <b>40</b>A and <b>40</b>B so that the movable lenses <b>34</b>A and <b>34</b>B move so as to approach to each other or retract in the optical axial direction. As a result, a scaling operation is performed by the objective optical system.

FIG. 1B shows a layout structure of the protective tube <b>21</b> and the linear transmission member <b>27</b> which correspond to the endoscope, and in the example concerned, these are divided into two respectively. More specifically, the protective tube <b>21</b> is divided into a front-side tube <b>21</b>A and a rear-side tube <b>21</b>B having larger diameters (inner diameter and outside diameter) than the front-side tube <b>21</b>A, and these are connected together within the operating unit <b>10</b>D. Also, the linear transmission member <b>27</b> is also divided into a front-side transmission member <b>27</b>A and a rear-side transmission member <b>27</b>B having a larger outside diameter than this front-side transmission member <b>27</b>A, and these are connected together within the soft portion <b>10</b>C.

FIG. 2 shows a detail drawing for the protective tube <b>21</b>A and <b>21</b>B, and a rear end portion of the front-side tube <b>21</b>A is fitted in the outer periphery of a first connecting barrel <b>44</b> to be bonded with adhesive or the like, and on the outside thereof, a thin-walled pipe <b>45</b> as a fastening member is arranged. On the outer periphery of this first connecting barrel <b>44</b>, there is formed a male threaded portion, and to a second connecting barrel <b>46</b>, formed with a female threaded portion for threadedly engaging this male threaded portion, having a larger inner diameter than the first connecting barrel <b>44</b>, there is mounted a rear-side tube <b>21</b>B. More specifically, in the outer periphery of the second connecting barrel <b>46</b>, the front end portion of the rear-side tube <b>21</b>B is fitted, is bonded with adhesive or the like, and the outside thereof is pressed with a thin-walled pipe <b>47</b>.

Also, on the inner periphery of the rear side of the first connecting barrel <b>44</b>, there is formed a tapered (conical) surface <b>45</b>A, which spreads toward the rear end port, in such a manner that there is caused no difference in level within the protective tube <b>21</b> by means of the tapered surface <b>45</b>A. The connecting portion between the tube <b>21</b>A and the tube <b>21</b>B based on the first connecting barrel <b>44</b> and the second connecting barrel <b>46</b> is arranged within the operating unit <b>10</b>D as described above, and the rear end portion of the rear-side tube <b>21</b>B is mounted to the holding member <b>18</b> of the FIG. <b>4</b>.

FIG. 3 shows a detail drawing for the linear transmission members <b>27</b>A and <b>27</b>B, and the front-side transmission member <b>27</b>A and the rear-side transmission member <b>27</b>B are connected together through a connecting member <b>48</b> as shown. A connecting portion of the linear transmission member <b>27</b> using this connecting member <b>48</b> is arranged midway in the soft portion <b>10</b>C as described above. According to the connecting portion, the rotation of the motor <b>19</b> can be satisfactorily transmitted to the rotary driving element <b>39</b> at the tip end portion <b>10</b>A by means of stable rotation of the linear transmission member <b>27</b>.

Also, in the example concerned, the rear-side transmission member <b>27</b>B is constructed so as to leave space for a single thread. That is, the linear transmission member <b>27</b> comprises coiled spring strands wound in multiple ways, and for example, five pieces of strands are wound in a spiral fashion so as to leave space for a single thread (at any intervals) as indicated by “e” in FIG. 3 in a state in which they are brought into tight contact, and this is doubled for formation. In this case, the friction between the rear-side transmission member <b>27</b>B, which rotates, and the protective tube <b>21</b>A, <b>21</b>B becomes less as compared with when no predetermined intervals are left.

According to the structure of the foregoing embodiment, the diameter of the rear-side tube <b>21</b>B has been made to be larger than the front-side tube <b>21</b>A to thereby be able to be separately handled, and therefore, the rear-side tube <b>21</b>B can be used as a standard tube applicable to all with the front-side tube <b>21</b>A made to have a size responsive to the type of the endoscope. Thereby, a mounting member for the tube <b>21</b>B concerned explained in FIG. 4 including the rear-side tube <b>21</b>B, that is, the holding member <b>18</b> and the fixture <b>20</b> can be caused to have the same structure for all different types of endoscopes.

Also, it is possible to set the inner diameter of the rear-side tube <b>21</b>B to such size as to smoothly rotate the linear transmission member <b>27</b> irrespective of the diameter of the insertion portion, and to enhance the transmission efficiency of rotation of the linear transmission member <b>27</b>. And yet, in the example concerned, the rear-side transmission member <b>27</b>B is constructed so as to leave space for a single thread, and the friction between the rear-side transmission member <b>27</b>B, and the front-side tube <b>21</b>A and the rear-side tube <b>21</b>B can be further reduced to further enhance the transmission efficiency of the linear transmission member <b>27</b>.

In this respect, in the foregoing embodiment, the front-side transmission member <b>27</b>A and the rear-side transmission member <b>27</b>B have been connected together within the soft portion <b>10</b>C, but it may be possible to connect within either the soft portion <b>10</b>C or the operating unit <b>10</b>D in the vicinity of the connecting portion between the front-side tube <b>21</b>A and the rear-side tube <b>21</b>B.

As described above, according to the present invention, the protective tube is divided into the front-side tube and the rear-side tube having a larger inner diameter than the front-side tube, and the front-side tube and the rear-side tube are connected together within the operating unit, and therefore, there are advantages that the friction between the linear transmission member and the protective tube is reduced as far as possible to thereby enhance the transmission efficiency of the motor driving force and that even when the endoscope is different in type, the structure of the operating unit-side driving unit can be made to be the same.

Also, according to another invention, as the rear-side linear transmission member, there has been used a multiple coiled spring comprising strands of a predetermined number of threads brought into tight contact wound so as to leave space for predetermined intervals, and therefore, the friction between the linear transmission member and the protective tube can be reduced to further enhance the transmission efficiency of the motor driving force.